JP2011020686A - Plastic bottle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plastic bottle that has high pressure resistance and impact resistance even when the plastic bottle has a thin wall in order to reduce its weight. <P>SOLUTION: The plastic bottle 10 is equipped with a mouth 11, a body 12, and a bottom 20. The bottom part 20 is provided with a center 24 and a plurality of feet 21 that are disposed around the periphery of the center 24 and that jut downwards. The strength of each foot 21 is increased as a result of one to six grooves 23, which extend in the radial direction of the bottom part 20 and indent inwards, being formed on each foot 21. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plastic bottle made of a synthetic resin such as polyethylene terephthalate, and more particularly to a plastic bottle with improved pressure resistance and impact resistance.

  In recent years, it has been desired to reduce the weight of plastic bottles by reducing the amount of plastic material used in the plastic bottles. However, when the bottle is lightened, the strength of the bottle is weakened. For this reason, the light weight bottle has restrictions such as being limited to designability and over-the-counter sales (hand sale) in order to maintain a certain strength.

  Also, when bottles are sold in vending machines, the bottles in the vending machine tend to be laid sideways and loaded, so that the bottles in the lower tier tend to be crushed. There is a tendency that the bottle cannot be discharged or the bottle is recessed during storage or discharge in the vending machine. In order to solve this, there is a technique of filling a bottle with liquid nitrogen or the like immediately after the bottle is filled with the content liquid in the process of manufacturing the bottle beverage, thereby positively increasing the bottle internal pressure and closing the bottle. Thereby, the inside of a bottle becomes a positive pressure and it is possible to raise the intensity | strength of a bottle. In addition, filling the inside of the bottle with an inert gas such as nitrogen as described above also has an effect of preventing the content liquid (for example, green tea) from being oxidized.

  Further, when natural foaming water (sparkling water) or oxygen water is filled in the bottle, the inside of the bottle is slightly positive. Alternatively, if the bottle is filled with content liquid such as green tea or coffee and the filling temperature is lower than the selling temperature, the volume of the inner solution expands by increasing the temperature difference between the selling and filling, and the inside of the bottle expands. Positive pressure.

  In this way, when the inside of the bottle has a positive pressure, when the bottle 100 having the bottom 101 having a general shape as shown in FIG. 7 is used, the bottom 101 is inflated due to the positive pressure in the bottle 100. The total height of 100 becomes high. Or the unevenness | corrugation of the bottom part 101 will reverse (buckling), and the bottle 100 will become independent.

  For this reason, the technique which makes a bottom part a petaloid shape in order to give pressure resistance to a bottle is known (patent documents 1). In addition to this, only the bottom peripheral part of the bottom part is formed thick to form a technique (Patent Document 2) corresponding to bottom part deformation and impact, and a plurality of ribs having a substantially inverted U-shaped side section projecting to the inside at the bottom part. Technology (Patent Document 3) exists.

Utility Model Registration No. 2551699 Japanese Patent Laid-Open No. 10-139029 Japanese Patent Publication No. 3-39897

  As shown in Patent Document 1, a plastic bottle having a petaloid-shaped bottom (hereinafter also referred to as a petaloid bottle) has excellent pressure resistance. However, when the petaloid bottle is reduced in weight, the bottom portion is also thinned, so that even when the inside of the bottle is pressurized, a dent tends to occur particularly when it is subjected to an impact due to dropping or the like. If such a dent occurs, it not only loses commercial value, but also causes load collapse during transportation and clogging in a vending machine.

  Moreover, since the petaloid bottle reduced in weight is thin at the bottom, the tip of the foot is easily deformed and stretched by pressurization, so that the overall height becomes higher than when no pressure is applied. When the total height is high, troubles such as being unable to enter the rack of the vending machine, not being able to enter the cardboard case, and causing the product to have a high center of gravity and to easily fall are likely to occur.

  On the other hand, it is difficult to apply the technique shown in Patent Document 2 to the bottom of a petaloid bottle. In other words, if only the bottom part is formed thick, the grounding of the bottle may become unstable due to poor cooling during blow molding, and the gate part (center part) of the bottle bottom part is likely to be deformed, and as a result, it becomes self-supporting. This is because sufficient bottle performance cannot be obtained.

  Moreover, since the bottle shown in patent document 3 is inferior to pressure | voltage resistant performance, the pressure in a bottle cannot be made very high.

  The present invention has been made in consideration of such points, and an object of the present invention is to provide a plastic bottle having high pressure resistance and impact resistance even when it is thinned for weight reduction. To do.

  The present invention is a plastic bottle, comprising a mouth, a trunk, and a bottom, the bottom having a central portion and a plurality of legs that are disposed around the central portion and project downward. The plastic bottle is characterized in that each leg portion is formed with one to six grooves extending along the radial direction of the bottom portion and retracting inward.

  According to the present invention, each leg has a grounding surface, a leg inner side surface provided on the inner side of the grounding surface, and a leg outer side surface provided on the outer side of the grounding unit, and each groove extends from the inner side surface of the leg part. It is a plastic bottle characterized in that it extends to the outer surface of the leg portion through the ground contact surface.

  The present invention is the plastic bottle characterized in that the bottom portion has 5 to 9 legs.

  The present invention is the plastic bottle characterized in that each leg has a ground contact surface, and the thickness of the ground contact surface is 0.04 mm to 0.3 mm.

  The present invention is the plastic bottle characterized in that each groove has a depth of 0.05 mm to 3 mm.

  The present invention is the plastic bottle characterized in that each groove has a length of 3 mm to 25 mm.

  The present invention is the plastic bottle characterized in that the width of each groove is 0.2 mm to 5 mm.

In the present invention, in each leg, the ratio of the total area (S _g ) of the bottom surface of each groove to the total area (S _T ) of the ground contact surface, the inner surface of the leg, and the outer surface of the leg is 2% or more and 50 It is a plastic bottle characterized by being less than%.

  The present invention is a plastic bottle characterized by having a structure in which a barrier layer having gas barrier properties and light shielding properties is laminated or a structure in which a resin having gas barrier properties and light shielding properties is blended.

  According to the present invention, one to six grooves extending along the radial direction of the bottom portion and retracting inward are formed in each leg portion of the bottom portion. Thus, even when the plastic bottle is thin in order to reduce the weight, the pressure resistance and impact resistance of the plastic bottle can be improved.

FIG. 1 is a front view showing a plastic bottle according to an embodiment of the present invention. FIG. 2 is a vertical sectional view showing the bottom of a plastic bottle according to one embodiment of the present invention. FIG. 3 is a perspective view showing the bottom of a plastic bottle according to an embodiment of the present invention. 4 is a perspective view showing the bottom of a plastic bottle according to Comparative Example 1 and Comparative Example 2. FIG. FIG. 5 is a graph comparing the total elongation of plastic bottles when the internal pressure of the bottle is increased. FIG. 6 is a graph comparing the gate depth elongation rate of a plastic bottle when the internal pressure of the bottle is increased. FIG. 7 is a view showing the bottom of the non-pressure-resistant bottle.

  Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 are views showing an embodiment of the present invention.

  First, the outline of the plastic bottle according to the present embodiment will be described with reference to FIGS. In the present specification, “upper” and “lower” refer to the upper and lower sides of the plastic bottle 10 in an upright state (FIG. 1), respectively.

  As shown in FIG. 1, a plastic bottle 10 made of a petaloid bottle includes a mouth part 11, a body part 12 provided below the mouth part 11, and a bottom part 20 provided below the body part 12. .

  This plastic bottle 10 is a preform produced by injection molding a synthetic resin material and biaxially stretch blow molded. In addition, it is preferable to use a thermoplastic resin, especially PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate) as a material of the preform, that is, the plastic bottle 10.

  The plastic bottle 10 can also be formed as a multilayer molded bottle having two or more layers. That is, by extrusion molding or injection molding, for example, the intermediate layer has gas barrier properties and light shielding properties such as MXD6, MXD6 + cobalt salt, PGA (polyglycolic acid), EVOH (ethylene vinyl alcohol copolymer) or PEN (polyethylene naphthalate). A multilayer bottle having gas barrier properties and light shielding properties may be formed by extrusion molding a preform composed of three or more layers as the resin (intermediate layer), and then blow molding. Such an intermediate layer is preferably provided in at least the body 12 of the plastic bottle 10. Moreover, it is preferable to provide an intermediate layer in the bottom portion 20 except for the central portion 24 (described later). This is because this portion may cause delamination (delamination) when subjected to an impact such as a case dropping. In order to have gas barrier properties and light shielding properties, a blend bottle in which thermoplastic resins are blended may be formed as well as multilayers.

  By the way, as shown in FIGS. 1 to 3, the bottom portion 20 of the plastic bottle 10 is provided with a substantially circular center portion 24 as viewed from the bottom surface direction, and is provided around the center portion 24 and arranged at equal intervals in the circumferential direction. And a plurality (five in FIG. 1 to FIG. 3) of leg portions 21 projecting downward.

  The number of the leg portions 21 can be 5 to 9. However, the number of the leg portions 21 is most preferably 5 to 7 from the viewpoint of stably erecting the plastic bottle 10 and improving the moldability of the light weight bottle.

  2 and 3, each leg 21 includes a grounding surface 21a, a leg inner side surface 21b extending upward from the grounding surface 21a toward the central portion 24, and a peripheral edge of the bottom 20 from the grounding surface 21a. A leg outer surface 21c extending upward toward the portion 20b. Among these, the leg inner side surface 21b has a substantially triangular shape when viewed from the bottom surface direction (see FIG. 3). The leg outer surface 21 c is connected to the lower end of the trunk 12 and is flush with the trunk 12.

  On the other hand, between each leg part 21, the curved surface 22 extended upward toward the peripheral part 20b of the bottom part 20 from the center part 24 is formed. As shown in FIG. 2, each curved surface 22 constitutes a part of a substantially spherical curved surface that curves downward.

  Each leg portion 21 is formed with an elongated groove 23 extending from the center portion 24 side to the peripheral edge portion 20b side along the radial direction of the bottom portion 20 and drawn into the plastic bottle 10 inward (substantially upward). Yes.

  As shown in FIGS. 1 and 3, three grooves 23 are formed in each leg portion 21. These three grooves 23 are composed of a groove 23a located at the center of the leg portion 21 and a pair of grooves 23b, 23b located on both sides of the groove 23a (see FIG. Groove 23).

  Note that the number of grooves 23 formed in each leg portion 21 is not limited to three, and may be one to six. When the number of the grooves 23 is 7 or more, as will be described later, when the plastic bottle 10 is produced by blow molding, there arises a problem with the shaping failure of the bottom portion 20.

  Each groove 23 extends from the leg inner side surface 21b to the leg outer surface 21c through the ground contact surface 21a. Thereby, the intensity | strength of the leg part 21 whole containing the grounding surface 21a is raised. The length of each groove 23 is preferably 3 mm to 25 mm, and the width of each groove 23 is preferably 0.2 mm to 5 mm.

  Further, the depth of each groove 23 is preferably 0.05 mm to 3 mm, and more preferably 0.8 mm to 1.2 mm. In addition, when the depth of each groove | channel 23 shall be less than 0.05 mm, the effect of this Embodiment of raising the intensity | strength of each leg part 21 is hard to be acquired. On the other hand, when the depth of each groove 23 exceeds 3.0 mm, there is a risk of forming defects when the plastic bottle 10 is blow-molded.

In each leg portion 21, the total area (S _g ) of the bottom surface 23 c (see FIG. 2) of each groove 23 with respect to the total area (S _T ) of the ground contact surface 21 a, the leg inner side surface 21 b, and the leg outer side surface 21 c. The ratio is preferably 2% or more and 50% or less (that is, 0.02 ≦ (S _g / S _T ) ≦ 0.5). When the ratio is less than 2%, it is difficult to obtain the effect of the present embodiment that increases the strength of each leg 21. On the other hand, when the ratio is more than 50%, there is a risk of forming failure when the plastic bottle 10 is blow-molded.

  The size of the plastic bottle 10 is not limited, and may be any size bottle.

  In the present embodiment, as described above, the three grooves 23 are formed in each leg portion 21, and the strength of each leg portion 21 is increased. As a result, even if the plastic bottle 10 is a thin-walled bottle, it is strongly resistant to deformation and hardly deformed. Specifically, the thickness of each leg portion 21 on the ground contact surface 21a can be set to 0.04 mm to 0.3 mm, particularly 0.05 mm to 0.25 mm.

  The object to be filled in the plastic bottle 10 is not limited, but the bottle internal pressure is made positive by using carbonated drinking water, natural foaming water (sparkling water), oxygen water, liquid nitrogen, etc. in which the inside of the plastic bottle 10 becomes positive after filling. Soft drinks are suitable. Here, the positive pressure inside the plastic bottle 10 means that the internal pressure of the plastic bottle 10 becomes 1 kPa to 400 kPa when the liquid temperature of the filled content liquid is 20 ° C. In particular, when the internal pressure of the plastic bottle 10 is 1 kPa to 150 kPa, the effect of the present embodiment is easily obtained.

  Next, the operation of the present embodiment having such a configuration will be described.

  First, the plastic bottle 10 is filled with a liquid content such as carbonated drinking water, natural foaming water (sparkling water), oxygen water, green tea, or coffee, and then liquid nitrogen is filled into the head space and then closed. . At this time, the inside of the plastic bottle 10 becomes a positive pressure (for example, when the liquid temperature of the content liquid is 20 ° C., the internal pressure immediately after filling is 1 kPa to 400 kPa) due to the filled inert gas or the content liquid.

  When the inside of the plastic bottle 10 becomes positive pressure, a force acts from the inside of the plastic bottle 10 to the outside, and pressure is applied to the bottom portion 20 from the upper side to the lower side. In this state, the plastic bottle 10 (hereinafter also referred to as a beverage product) filled with the contents is shipped, transported to a retail store or put into a vending machine and sold to a consumer.

  By the way, in the present embodiment, each leg portion 21 is formed with three grooves 23 extending along the radial direction of the bottom portion 20 and retracting inward. Therefore, even if the pressure in the plastic bottle 10 becomes positive and a substantially downward force is applied to the bottom portion 20, the strength of each leg portion 21 is increased, and the overall height of the plastic bottle 10 does not change greatly. This prevents troubles such as the plastic bottle 10 not entering the rack of the vending machine or the cardboard case.

  In addition, since the strength of each leg portion 21 is increased, even when an impact is applied to the bottom portion 20 in a state where the inside of the plastic bottle 10 is at a positive pressure, the leg portion 21 is deformed such as a dent. Is unlikely to occur. Thereby, it is possible to prevent the commercial value of the plastic bottle 10 filled with the contents from being damaged, and to prevent the collapse of goods during transportation and the clogging in the vending machine.

  In particular, such an effect is more prominent when the plastic bottle 10 is formed thin (that is, when the thickness of the ground contact surface 21a is 0.04 mm to 0.3 mm as described above).

  As described above, according to the present embodiment, each leg portion 21 is formed with one to six grooves 23 extending along the radial direction of the bottom portion 20 and retracting inward, so that the weight can be reduced. Even when the plastic bottle 10 is thin, the pressure resistance and impact resistance of the plastic bottle 10 can be improved.

  Also, according to the present embodiment, each groove 23 extends from the leg inner side surface 21b to the leg outer side surface 21c through the ground contact surface 21a, so that the strength of the entire leg portion 21 is increased.

  Next, specific examples of the present embodiment will be described with reference to FIGS.

Example 1
First, as shown in FIG. 1, a plastic bottle 10 (Example 1) for 500 ml in which three grooves were formed in the leg portion 21 of the bottom portion 20 was produced. In this case, the plastic bottle 10 (Example 1) was produced by carrying out biaxial stretch blow molding of 18g preform. This plastic bottle 10 (Example 1) is made thinner than a plastic bottle generally used conventionally.

(Comparative Example 1)
A 500 ml plastic bottle 50 (Comparative Example 1) shown in FIG. 4 having the same thickness as that of Example 1 except that no groove is formed in the leg portion 52 of the bottom 51. Was made.

(Comparative Example 2)
A 500 ml plastic bottle 70 (Comparative Example 2) shown in FIG. 4 was produced in the same manner as in Comparative Example 1 except that it was formed thick. In this case, a plastic bottle 70 (Comparative Example 2) was produced by biaxially stretching blow molding a 28 g preform. This plastic bottle 70 (Comparative Example 2) has a thickness 1.5 to 4 times that of the plastic bottle 10 of Example 1.

  Next, an inert gas was injected into these three types of plastic bottles 10, 50, and 70, and each was sealed with a positive pressure (50 kPa).

(Case drop test)
Next, 24 of each of the three types of plastic bottles 10, 50, and 70 were accommodated in a case, and the cases were collectively dropped (case dropped) from a height of 50 cm. Subsequently, for each of the plastic bottles 10, 50, and 70, the number of recessed bottles and the area of the recessed portions among the 24 bottles were quantified and compared (Table 1).

  As a result, with respect to the plastic bottle 10 of Example 1, there was no bottle with dents. Thus, by forming the three grooves in the leg portion 21, the number of dents and the dent area were greatly improved as compared with the plastic bottles 50 and 70 of Comparative Examples 1 and 2.

(Verification by vending machine)
Next, 12 of each of the three types of plastic bottles 10, 50 and 70 were put into the vending machine, and the discharge suitability from the vending machine and the presence or absence of dents in the bottle were verified (Table 2).

  As a result, for the plastic bottle 10 of Example 1, there was no bottle with poor carry-out suitability, and there was no bottle with dents. As described above, by forming the three grooves in the leg portion 21, the carry-out suitability and the recessed area are greatly improved as compared with the plastic bottle 50 of Comparative Example 1. In addition, as for the plastic bottle 70 (Comparative Example 2) generally used in the past, there were no bottles with poor carry-out suitability and bottles with dents.

(Measurement of total elongation and gate depth elongation)
Next, when the internal pressures of the three types of plastic bottles 10, 50, and 70 were increased from 0 kPa to 110 kPa, the total high elongation rate and the bottom gate depth elongation rate of each plastic bottle were measured. Here, the total height elongation refers to a value obtained by dividing the amount of change in the total height of the plastic bottle based on the total height of the plastic bottle when the internal pressure is 0 kPa by the total height of the plastic bottle when the internal pressure is 0 kPa. The gate depth elongation rate is the value obtained by dividing the amount of change based on the gate depth of a plastic bottle with an internal pressure of 0 kPa by the gate depth of the plastic bottle when the internal pressure is 0 kPa. A large value indicates that the plastic bottle has a large dimensional change. The gate depth means the distance in the height direction between the center of the bottom of each bottle (for example, the center 24 in the first embodiment) and the bottle grounding surface. The results are shown in FIGS.

  As a result, the total height of the plastic bottle 10 according to Example 1 increased as the internal pressure increased (FIG. 5), and the gate depth of the bottom portion 20 decreased (FIG. 6). However, although the plastic bottle 10 according to Example 1 is thinner than the plastic bottle 70 (Comparative Example 2), the total high elongation rate and the gate depth elongation rate are the plastic bottle 70 (Comparative Example 2). ) And higher than that (FIGS. 5 and 6).

  On the other hand, as for the plastic bottle 50 of Comparative Example 1, compared with the plastic bottle 10, the total high elongation rate and the gate depth elongation rate were large.

(Number of grooves and blow moldability)
(Comparative Example 3)
500 ml plastic bottle having the same wall thickness as in Example 1 except that seven grooves are formed in each leg so that S _g / S _t ≧ 50%. (Comparative Example 3) was produced. In this case, a plastic bottle (Comparative Example 3) was produced by biaxially stretching blow molding an 18 g preform.

  As a result, regarding the plastic bottle of Comparative Example 3, a shaping failure occurred during blow molding. This is considered to cause shaping defects when the number of grooves is 7 or more.

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Mouth part 12 Trunk part 20 Bottom part 20b Peripheral part 21 Leg part 21a Grounding surface 21b Leg part inner side surface 21c Leg part outer side surface 22 Curved surface 23 Groove 23c Bottom face 24 Center part

Claims (9)

In plastic bottles,
The mouth,
The torso,
With a bottom,
The bottom portion has a central portion and a plurality of legs disposed around the central portion and projecting downward,
A plastic bottle characterized in that one to six grooves extending along the radial direction of the bottom portion and retracting inward are formed in each leg portion. Each leg has a grounding surface, a leg inner surface provided on the inner side of the grounding surface, and a leg outer surface provided on the outer side of the grounding part
2. The plastic bottle according to claim 1, wherein each groove extends from the inner surface of the leg portion to the outer surface of the leg portion through the ground contact surface.   The plastic bottle according to claim 1 or 2, wherein the bottom has 5 to 9 legs.   The plastic bottle according to any one of claims 1 to 3, wherein each leg portion has a grounding surface, and the thickness of the grounding surface is 0.04 mm to 0.3 mm.   5. The plastic bottle according to claim 1, wherein each groove has a depth of 0.05 mm to 3 mm.   6. The plastic bottle according to claim 1, wherein each groove has a length of 3 mm to 25 mm.   The plastic bottle according to any one of claims 1 to 6, wherein the width of each groove is 0.2 mm to 5 mm. In each leg, the ratio of the total area (S _g ) of the bottom surface of each groove to the total area (S _T ) of the ground contact surface, the inner surface of the leg, and the outer surface of the leg is 2% or more and 50% or less. The plastic bottle according to any one of claims 1 to 7, wherein   9. It has a structure in which a barrier layer having a gas barrier property and a light shielding property is laminated, or has a structure in which a resin having a gas barrier property and a light shielding property is blended. The described plastic bottle.

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